Low speed high torque rotary drive for turning a furnace vessel or the like

ABSTRACT

A high output torque for low speed rotation of a heavily laden furnace vessel or the like is provided by a fluid energizing rotary drive in which a plurality of actuating cylinders are connected with a driving crank by a common eccentric connector rotatably stabilized and journalled on the crank. Energization of the actuating cylinders by fluid under pressure is automatically synchronized with rotation of the driving crank so that the cylinders all work together to urge the driving crank in the same rotary direction. A fluid energizing system operates, on stored energy if necessary, under the control of a master control valve to effect rotation of the drive in either direction and to forcefully but progressively decelerate the drive to a standstill where it is held, all by means of the actuating cylinders.

United States Patent 1191 Stafford June 12, 1973 LOW SPEED HIGH TORQUE ROTARY DRIVE FOR TURNING A FURNACE VESSEL Primary Examiner.l. Spencer Overholser OR THE LIKE Assistant Examiner-John S. Brown [76] Inventor: Milton c. Stafford, 624 South Hamby Michigan Avenue, Tinley Park, 11]60605 [57] ABSTRACT A high output torque for low speed rotation ofa heavily [22] Ffled: 1971 laden furnace vessel or the like is provided by a fluid [21] Appl. No.: 117,234 energizing rotary drive in which a plurality of actuating cylinders are connected with a driving crank by a c0mmon eccentric connector rotatably stabilized and jour- [52] US. Cl. 266/36 P naned on the crank Energization of the actuating [51] ll lt. Cl. C216 5/50 inders by fluid under pressure is automatically synchro [58] FlBld 0f Search 266/36 R, 36 H; nized with rotation of the driving crank so that the 91/170 1721 inders all work together to urge the driving crank in the 196 same rotary direction. A fluid energizing system operates, on stored energy if necessary, under the control [56] References of a master control valve to effect rotation of the drive UNITED STATES PATENTS in either direction and to forcefully but progressively 3,053,053 9/1962 Douglas 91/171 decele ate t e d e t a s ds w ere t is eld, a l 3,307,841 3/1967 Lixenfield.... 266/36 P by means of the actuating cylinders. 3,310,298 3/1967 Huwyler 266/36 P 3,531,074 9/1970 Zelley 3 Chums 5 Drawmg Flgures 3,512,597 5/1970 Baron 91/170 R X PATENTED JUN 1 2 3. 738.630

MEI 2 0f 3 LOW SPEED HIGH TORQUE ROTARY DRIVE FOR TURNING A FURNACE VESSEL OR THE LIKE The present invention relates to a low speed, high torque rotary drive which is particularly useful in conjunction with a basic oxygen furnace for rotating the heavily laden furnace into tapping position. Conventional furnaces equipped with rotary drives of the prior art have suffered a number of disadvantages and shortcomings that are avoided by the present invention which provides distinct advantages on its own account.

One object of the invention is to provide an improved furnace which is rotated into tapping position by means of a high torque, low speed rotary drive energized by operating fluid under pressure and having a new and improved construction affording many significant advantages in this environment.

Another object is to provide, for dumping a rotatable furnace or the like, a high torque, low speed rotary drive energized by operating fluid under pressure and having a novel and advantageous construction that minimizes to great advantage the space within the immediate vicinity of the part to be rotated that is re-,

quired to accommodate the essential drive structure.

Another object is to provide a low speed, high torque drive energized by fluid under pressure and having a construction that permits removal and replacement of most working parts requiring maintenance while at the same time keeping the drive in service and fully operative.

Another object is to provide a fluid energized, high torque, low speed drive in accordance with the preceding objects that is capable of accommodating extensive relative movement of working parts, due to elastic deformation of the structure under stress or otherwise, without adverse effect on the drive structure or is functionality.

A further object is to provide a low speed, high torque drive in accordance with the preceding objects that is inherently economical to manufacture and install, most reliable in operation, and notably economical to operate and service.

An additional object is to provide, as for dumping molten metal from a vessel, a low speed, high torque drive that will function dependably to rotate the driven structure even in the event of a power failure or other failure of the prime mover that energizes the drive.

Other objects and advantages will become apparent from the following description of the exemplary embodiments of the invention illustrated in the drawings, in which:

FIG. 1 is an elevational view showing the rotary drive of the invention applied to the rotatable vessel, illustrated schematically, of a basic oxygen furnace that is rotated to dump a batch of molten metal;

FIG. 2 is an inclined plan view taken generally with reference to the line 2-2 of FIG. 1, with certain parts broken away to better reveal internal construction;

FIG. 3 is a sectional view taken with reference to the line 3-3 of FIG. 2 and showing cam controlled reversing valves for power actuating cylinders of the drive that are operated in synchronism with rotary movement of the drive;

FIG. 4 is a sectional view similar to FIG. 3 but showing the relative position of the parts as the drive passes through dead center positions in relation to successive fluid actuating cylinders incorporated in the drive; and

FIG. 5 is a diagrammatic illustration of the fluid power system used in energizing and controlling the drive.

Referring now to the drawings in greater detail, the basic oxygen furnace incorporating the exemplary embodiment of the invention illustrated comprises a large vessel 12, illustrated schematically in FIGS. 1 and 2, adapted to contain a heavy charge of molten metal. The heavily laden furnace or vessel 12 is supported as shown by a trunnion assembly comprising a trunnion ring 13 encircling a medial portion of the vessel to which the ring is attached by a series of circumferentially spaced brackets l5.'A pair of coaxial trunnions 14 fixed to the trunnion ring 13 project outwardly in opposite directions from the trunnion ring and are journalled in pillow blocks 16. After being processed in the usual manner in the basic oxygen furnace 12, the charge 18 of molten metal in the furnace is tapped from the furnace by rotating the furnace about the common axis 20 of the support trunnions 1.4 to a position, FIG. 1, where the molten charge can drain out a tap hole 17.

Turning of the heavily laden vessel 12 to dump the heavy molten charge 18 requires the application of a very high torque to the vessel, which can be rotated very slowly. Component elements of drive structure used to turn the furnace vessel are subject to what can be troublesome deformation due to strain under applied load that can be complicated by thermal expansion of the parts.

The low speed, high torque rotary drive 22 provided by applicants invention to rotate the heavily laden vessel 12 uses the energy of fluid under pressure to develop the necessary torque required and comprises a radially projecting cranking element or crank 24 having a hub 26 encircling the end of a vessel support trunnion 14 which projects through a coacting pillow block 16 as illustrated in FIG. 2.

The cranking element 24 is firmly secured removably to the coacting trunnion 14 for rotation with the trunnion about the axis of rotation 20, the cranking element 24 in this instance being fixed in torque transmitting re lation to the coacting trunnion 14 in the construction illustrated by two pairs of split tapered tangential keys 28 accommodated in keyways 29, 31 in the trunnion l4 and crank hub 26 as shown in FIGS. 2-4. The two keys of each pair are forced firmly into coacting rela' tion with each other and adjacent parts in the present instance by a pressure applying screw 30 engaging one of the keys and being threadedly supported in a heavy cover plate 32 secured by screws or bolts 34 to the hub 26 and to the adjacent trunnion 144 in covering relation to the end of the trunnion, as illustrated in FIG. 2.

An orbital connector plate or element 36 is journalled on the cranking element 24 for rotation on the cranking element 24 about an orbital axis 38parallel to the axis of rotation 20 of the crank 24 and located in radially spaced eccentric relation to the axis 20 to orbit about the latter upon rotation of the crank 24. In the construction illustrated, the connector element 36 is journalled on an eccentric stub shaft 40 carried bythe crank 24.

A plurality of nonparallel linear forces are applied in unison to the connector element 36 by a plurality of longitudinally elongated actuating cylinders 42 energized by fluid under pressure. In the preferred embodiment shown, six double-acting hydraulic power cylin" ders 42 are used, each cylinder 42 including a reversibly extensible power plunger 44 projecting from one end of the cylinder.

The actuating cylinders 42 are individually pivoted respectively at one end to the connector element 36 to extend away from the connector element 36 in diverging relation to each other. As shown, the outer end of the extensible plunger 44 of each cylinder 42 is threaded into a coupling 46 which extends into straddling relation to the connector element 36 to which the coupling is pivoted by a pin 48 as shown in FIG. 2.

The opposite ends of the actuating cylinders 42 are anchored to stationary support structure, denoted generally in FIG. 1 by the number 50, radially spaced a substantial distance from the orbital path of the connector element 36 incident to rotation of the crank 24. The actuating cylinders 42 diverge away from the connector element 36, as mentioned, and are anchored to the stationary structure 50 at positions selected to best accommodate the drive 22 within the space available and to accommodate other environmental structure while at the same time conforming the maximum torque capacity of the drive to the torsional requirements of the drive in relation to the changing rotary position of the cranking element 24 as will presently appear.

In this connection, it will be appreciated that the torque which must be applied to the driving trunnion 14 to effect dumping of molten metal of the vessel 12 is not the same for all rotary positions of the vessel 12. Thus, the torque required to continue a' rotary movement of the vessel 12 such as is illustrated in'FIG. 1 and represented by the arrow 52 may substantially exceed the torque required to initiate turning movement or the torque required to continue rotation of the vessel after it has passed through the angular position where the maximum torque may be required to turn the vessel and its load, the center of gravity of which can be radially displaced from the axis 20 about which the vessel rotates.

As shown, the ends of the cylinders 42 remote from the connector element 36 are swingably supported on the anchoring structure 50 by pivot pins 54 extending through anchoring brackets 56 on the support structure 50 and coacting brackets 58 on the actuating cylinders.

As previously indicated, there may be substantial movement of the crank 24 relative to the anchoring structure 50 as the parts are strained by applied loads and exposed sometimes to thermal expansion and contraction. This movement is readily accommodated by the pivotal connections between the individual cylinders 42 and the anchoring structure 50 and connector element 36 as well as by the inherent ability of the cylinders 42 to expand and contract longitudinally.

Additional flexibility for accommodating deformation of the working parts by applied loads or by any other factors tending to cause misalignment of the parts is accommodated by swivel bearings 60 mounted in the connector element 36 to support the pivot pins 48 and by swivel bearings 62 mounted in the anchor brackets 56 to accommodate the pivot pins 54, the swivel bearings 60, 62 allowing universal swinging movement of the individual power cylinders 42 in relation to both the connector element 36 and the anchor brackets 56 while continuously maintaining the essential pivotal connections to opposite ends of each cylinder.

As shown in FIG. 1, the pivots 48 connecting the respective cylinders 42 with the connector element 36 are arrayed in a crescent-shaped pattern with the consequence that the vectors of the linear forces applied to the connector element 36 by the respective cylinders 42 are kept close to the eccentric axis 38 about which the connector element 36 turns and the total moment of such applied forces about the axis 38 is minimized.

To assure stabilization of the connector element 36 rotatably even when the forces applied by the cylinders 42 are unbalanced rotatably about the axis 38, a first guide 64 is swingably mounted on a stationary support 66 in spaced relation to the orbital path of the connector element 36 to swing about a pivotal axis 68. The guide 64 slidably receives an elongated guide 70 fixed to the connector element 36 and projecting radially through the guide 64. As shown, the guide 70 is in the form of a rod extending through a sleeve bearing 72 in the guide 64. Preferably, the guide rod 70 has a rectangular shape in transverse section. As the connector element 36 orbits about the axis 20, the guide 70 slides back and forth through the guide 64 to preclude rotation of the connector element 36 relative to the guide 64 which swings about the remotely positioned pivotal axis 68 with the consequence that any unbalance in the linear forces applied by the cylinders 42 to the connec-e tor element 36 will not effect turning movement of the connector element about the axis 38.

Having reference to the position of the parts as illustrated in FIG. 1, for example, the application of fluid under pressure to the several cylinders 42 to urge extension of all the plungers 44 simultaneously applies to the common connector element 36 forces having components which act about the eccentric axis 38 on the crank 24 to produce a powerful cumulative torque tending to turn the crank 24, the connected trunnion l4 and vessel 12 in the counterclockwise direction, with reference to FIG. 1, to effect dumping of the load 18 of molten metal.

As rotary movement of the drive continues, the power cylinders 42 pass successively through dead center positions in relation to the coacting linkage with a consequent reversal of the torque produced about the axis 20 by a linear force applied in a given direction by an individual power cylinder 42.

As the actuating cylinders 42 move successively through such dead center positions, the application of operating fluid under pressure to the individual cylinders is reversed for the cylinders in succession. It will be understood that such a reversal of the connection of operating fluid under pressure to an individual cylinder will change the output force of the cylinder from a plunger extending force to a plunger retracting force or vice versa.

In the construction illustrated, the valve means used to effect automatic reversal of the connection of fluid under pressure to the successive actuating cylinders moving through dead center positions comprises six reversing valves 74 connected in controlling relation re spectively to the six actuating cylinders 42 and being operated as shown by six cam followers 76 for the respective valves 74 which engage a circular valve control cam 78 rotatable with the crank 24 and mounted as shown adjacent the crank 24 in encircling relation to the coacting trunnion 14. Each reversing valve 74 is connected to opposite ends of the elongated fluid chamber 80 of the corresponding actuating cylinder 42 through two conduit lines 82, 84, illustrated in FIG. 2 for a typical cylinder 42.

As shown, the cam '78 is a single lobe cam shaped so that the two opposite ends 86, 88 of the single lobe 90 of the cam move past the cam followers 76 of the reversing valves 74 to reverse the application of actuating fluid to the respective cylinders 42 moving through dead center positions so that all the cylinders 42 operate substantially continuously to apply either plunger extending or plunger retracting forces to the connector element 36 so that such forces applied to the connector element 36 operate cumulatively to apply torque about the rotary axis of the crank 24. Thus, the drive will operate, if need be, by virtue of the automatic reversal of fluid under pressure to the actuating cylinders 42 in succession to turn the crank 24 continuously in either direction about the shaft 24, which direction is determined as will presently appear by a master control valve 92, FIG. 5.

As shown diagrammatically in FIG. 5, the master control valve 92 is a part of a fluid pressure energizing system, denoted generally by the number 94, comprising a reservoir 96 for hydraulic operating fluid which is fed to a pump 98 driven by a motor 100 and having outlet 102 connected through a check valve 104 with a high pressure fluid supply line 106 leading to the master control valve 92.

By means of the master control valve 92, the high pressure fluid supply line 106 is connected selectively either to a first distribution line 108 leading to one port of each of the reversing valves 74 or to a second distribution line 110 leading to a second port of each of the reversing valves 74. The master control valve 92 functions to connect the high pressure line 106 to either of the distribution lines 108 or 110 while simultaneously connecting the other distribution line through a flow restriction orifice 112 to exhaust back to the reservoir 96. If desired, the flow restriction orifice 112 which limits, as will presently appear, the speed of rotation of the drive may be combined with the master control valve 92. Thus, by suitable design the master control valve can be made to function as a metering valve to control the speed of rotation of the drive.

Operation of the master valve 92 to connect the supply line 106 with the distribution line 108, for example, supplies fluid under pressure through all the reversing valves 74 to the actuator cylinders 42 in unison to effect turning of the driven trunnion 14 in one predetermined direction, the reversing valves 74 having been conditioned by the cam 78 to cause all the cylinders 42 to individually elongate or contract selectively under the force of fluid pressure to work cumulatively in generating torque in the desired direction.

As rotation of the drive progresses, fluid from all of the cylinders 42 is exhausted through the other line 110 and throttled by the stricture 112 so that the maximum speed of rotation is limited as desired. A throttling valve 113, which can be combined with stricture 112 or the control valve 92, is placed in the line 110 and functions to controllably reduce the rotary speed of the drive to any reduced speed desired.

Reversing of the valve 92 applies fluid under pressure to the other distribution line 110, thus reversing the direction of application of fluid pressure to all the actuating cylinders 42 in unison so that the operating torque applied to the connected trunnion 14 by the drive is reversed with consequent reversal of the direction of rotary movement of the drive.

As indicated by the blockage ports 1141, the master control valve 92 can be shifted to an intermediate position to simultaneously block the exhaust from both distribution lines 108, 110 and the supply of fluid pressure to both lines with the consequence that the cylinders 42 are all precluded from either elongating or contracting and function to lock the drive and the vessel 12 in any position against rotation.

It will be appreciated that the master control valve 92 can be shifted into position for stopping rotation of the drive even when the drive and the heavily laden furnace vessel 12 are being actively rotated at full speed. Under these circumstances, it is undesirable that the rotating structure be brought immediately to a sudden halt as the rather substantial kinetic energy in the rotating structure would subject the drive, including the hydraulic system, to a heavy shock. To protect the system from such shock and to effect a progressive but rapid deceleration of the moving structure to a stop, after the valve 92 has been operated to terminate rotation of the drive, two pressure relief valves 116, 118 are connected between the flow distribution lines 108, 110 so that pressure building up in either line above a predetermined working limit, as an incident to operation of the valve 92 to stop the drive, is relieved by a throttled discharge of fluid from the line subjected to such higher pressure to the other flow distribution line which feeds the then low pressure ends of the respective cylinders .42. The rotating structure is quickly decelerated to a stop where it is held until released by subsequent oper ation of the control valve 92.

As shown, the distribution lines 108, 110 and associated parts are protected from any abnormally excessive pressure by a plurality of pressure-relief valves 120, 122. Check valves 125, 127 connect the respective lines 108, 110 with the reservoir 96 so that fluid rather than air is drawn into the lines 108, 110 and cylinders 42 in the event internal pressure tends to drop below atmospheric.

To provide a reservoir of operating fluid under pres sure sufficient to effect dumping of a load of molten metal from the vessel 12 even in the event of a power failure or a malfunction which precludes effective operation of the pump 98, an accumulator 124 is connected through a manual shutoff valve 126 with the supply line 106. A reserve supply of operating fluid received into the accumulator is maintained under pres sure by air pressure within a plenum space 128 in the upper region of the accumulator. in the event that an excessive amount of fluid reserve is forced out of the accumulator 124, an automatic shutoff valve 129 in series with manual valve 126 is activated to preclude the entrance of gas from the plenum space 128 into the distribution line 106.

In the event the drive 22 need operate only intermittently as is required in dumping the vessel 12, the pump 98 and driving motor need not be designed with sufficient capacity to produce fluid under operating pressure at the rate required to operate the drive at the desired speed, the operating fluid being supplied during such intermittent operation of the drive from both the pump 98 and the accumulator 124. The pump 98 can be operated while the drive is inactive to restore thereserve of fluid under pressure in the accumulator 124.

It will be appreciated that in installations where it may be desirable to use more than one rotary drive 22, it may not be necessary to duplicate the operating fluid supply structure for each additional drive, using one supply system to selectively energize a plurality of drives.

Because of its utter simplicity, the journalled connection between the connector element 36 and the crank 24 needs little servicing and is not subject to failure. The same applies to the journal support for the crank 24 as fixed to the coacting trunnion 14. The simple control cam for the synchronizing valves 74 is not subject to disorder. In the event any of the actuating cylinders 42 or their control valves 74 need service, an actuating cylinder or valve requiring service can be readily disconnected from the coacting structure, removed and subsequently replaced without disabling the drive or rendering it inoperative to serve its intended function.

The drive 22 is designed with sufficient power capacity to allow such removal of an actuating cylinder or re versing valve for service while maintaining an adequate operational capability. Duplicate master control valves 92 can be incorporated into the system, if desired, thus providing effective control by either master valve. As a consequence, all operational parts that may require service can be serviced and the drive can, in effect, be rather effectively overhauled without being taken out of service, which is a decided advantage particularly in a furnace where the drive need be continuously available and operable to dump the vessel 12.

The invention is claimed as follows:

1. A metal processing furnace comprising a vessel adapted to contain a charge of molten metal and having a pair of trunnions supporting the vessel for rotation about a horizontal axis, a cranking element fixed to one of said trunnions to rotate-therewith in driving relation thereto to rotate said vessel for tapping, a connector element journalled on said cranking element in eccentric relation to said axis, a swingable first guide, stationary anchoring means swingably supporting said first guide for swinging movement about a pivotal axis spaced from said connector element, a second guide fixed to said connector element and coacting with said first guide to hold said connector element against rotation relative to said first guide, a plurality of doubleacting fluid power cylinders individually energized reversibly by fluid under pressure, each cylinder being longitudinally elongated and including a reversibly extensible power plunger, said cylinders being pivotally connected respectively at one end to said connector element and extending away therefrom in diverging relation to each other, stationary anchoring means pivotally anchoring each cylinder at the end thereof more remote from said connector element, a pressurized fluid energizing system including master control valve means connected with said power cylinders for selectively supplying operating fluid to said cylinders reversibly and in unison to turn said vessel selectively in either direction about said axis of rotation of the vessel by torque generated by linear forces applied by said cylinders to said connector element, valve control means rotatable with said cranking element, and a plurality of reversing valve means operated by said valve control means and being interconnected with said respective cylinders to reverse the supply of operating fluid to each individual cylinder as the cylinder moves through to either end of its stroke during rotation of said vessel.

2. A metal processing furnace according to claim 1 comprising a first plurality of universally swingable joints pivotally connecting said respective cylinders to said connector element and a second plurality of universally swingable joints pivotally connecting the opposite ends of said respective cylinders to the stationary anchoring means.

3. A metal processing furnace comprising a vessel adapted to contain a charge of molten metal and having a pair of trunnions supporting the vessel for rotation about a horizontal axis, a cranking element connected with one of said trunnions to rotate therewith in driving relation thereto to rotate said vessel for tapping, a connector element journalled on said cranking element in eccentric relation to said axis, a plurality of elongated fluid power cylinders energized individually by fluid under pressure to forcibly change the lengths of the respective cylinders, said cylinders being pivotally connected respectively at one end to said connector element and extending away therefrom in diverging relation to each other, stationary anchoring means pivot ally anchoring each cylinder at the end thereof more remote from said connector element, and operating fluid supply means connected with said power cylinders for selectively supplying operating fluid to said cylinders under pressure to turn said vessel about said axis by torque generated by forces applied by said cylinders to said connector element. 

1. A metal processing furnace comprising a vessel adapted to contain a charge of molten metal and having a pair of trunnions supporting the vessel for rotation about a horizontal axis, a cranking element fixed to one of said trunnions to rotate therewith in driving relation thereto to rotate said vessel for tapping, a connector element journalled on said cranking element in eccentric relation to said axis, a swingable first guide, Stationary anchoring means swingably supporting said first guide for swinging movement about a pivotal axis spaced from said connector element, a second guide fixed to said connector element and coacting with said first guide to hold said connector element against rotation relative to said first guide, a plurality of double-acting fluid power cylinders individually energized reversibly by fluid under pressure, each cylinder being longitudinally elongated and including a reversibly extensible power plunger, said cylinders being pivotally connected respectively at one end to said connector element and extending away therefrom in diverging relation to each other, stationary anchoring means pivotally anchoring each cylinder at the end thereof more remote from said connector element, a pressurized fluid energizing system including master control valve means connected with said power cylinders for selectively supplying operating fluid to said cylinders reversibly and in unison to turn said vessel selectively in either direction about said axis of rotation of the vessel by torque generated by linear forces applied by said cylinders to said connector element, valve control means rotatable with said cranking element, and a plurality of reversing valve means operated by said valve control means and being interconnected with said respective cylinders to reverse the supply of operating fluid to each individual cylinder as the cylinder moves through to either end of its stroke during rotation of said vessel.
 2. A metal processing furnace according to claim 1 comprising a first plurality of universally swingable joints pivotally connecting said respective cylinders to said connector element and a second plurality of universally swingable joints pivotally connecting the opposite ends of said respective cylinders to the stationary anchoring means.
 3. A metal processing furnace comprising a vessel adapted to contain a charge of molten metal and having a pair of trunnions supporting the vessel for rotation about a horizontal axis, a cranking element connected with one of said trunnions to rotate therewith in driving relation thereto to rotate said vessel for tapping, a connector element journalled on said cranking element in eccentric relation to said axis, a plurality of elongated fluid power cylinders energized individually by fluid under pressure to forcibly change the lengths of the respective cylinders, said cylinders being pivotally connected respectively at one end to said connector element and extending away therefrom in diverging relation to each other, stationary anchoring means pivotally anchoring each cylinder at the end thereof more remote from said connector element, and operating fluid supply means connected with said power cylinders for selectively supplying operating fluid to said cylinders under pressure to turn said vessel about said axis by torque generated by forces applied by said cylinders to said connector element. 